When created, it has a 2-minute charge time. Once charging is complete, the player can choose any spot on the map to make vehicles, buildings, defenses or naval units invulnerable. The affected entities in the area will be invulnerable to enemy fire for 20 seconds.
Infantries are not affected, and are not killed by an iron curtain (as is the case in some C&C games such as Red Alert 2)
Demolition trucks explodes when the iron curtain is used on them.
A player can only build a single iron curtain.
The iron curtain can make 5 vehicles invulnerable at a time. Its area of effect is a 5-cell cross shape. When a Soviet player is creating this shape, it is a good indication an iron curtain is about to be used.
The iron curtain can be used to mitigate atom bomb attacks by making key structures invulnerable. See the atom bomb article for details.
To counter heavy artillery fire, iron curtained mobile flaks can be used because they are fast and extremely effective against artillery units.